President Obama’s got game — and that goes a long way to explaining why he said Tuesday that he’s more worried about a “nuclear weapon going off in Manhattan” than about Russia’s aggression in the Balkans.

Yes, he was confronting the buzz over the prescience of Mitt Romney, who in a 2012 debate told Obama (to much derision) that Russia is a top adversary that must be confronted.

But Obama was also likely recalling the simulation game he’d played with world leaders earlier in the day.

The simulation featured actors playing a band of terrorists who’d obtained a nuke. (To avoid political-correctness problems, the scenario didn’t mention the bad guys’ goals, affiliation or religion.) The play-terrorists were about to bomb the downtown of some city (again, no specification).

So Obama and other real leaders of the world’s top powers punched out choices on their tablets, indicating what they’d do as the crisis intensified.

Obama loved it.

Would the game have played out differently had it been designed in China rather than Holland? It’s certainly hard to see anyone being convinced by the fact that the way to “win” a simulation was to take the cooperative approach the White House advocates.

To be fair, one theme of the summit that brought Obama, German Chancellor Angela Merkel, French President Francois Hollande, British Prime Minister David Cameron, Chinese President Xi Jinping et al to The Hague was nuclear non-proliferation. Hence the game.

Then, too, simulation is a hot trend for academics, business executives, military planners and political war-roomies. In other words, it’s something 21st century leaders do.

But as the world’s top leaders maneuvered their tablets through a simulated crisis, the guy who was disinvited — Russia’s Vladimir Putin — amassed real tanks and well armed-troops on the eastern border of Ukraine, which Russia hints it may yet invade.

That, Obama & Co. keep reminding us, is 19th century behavior. As the president told young Europeans Wednesday, “Russia’s leadership is challenging truths that only a few weeks ago seemed self-evident, that in the 21st century the borders of Europe cannot be redrawn with force.”

Question is, how does a 21st century sophisticate answer a 19th century brute? So far the answer seems to be, mainly by wagging a finger.

Obama rescinded Putin’s invitation to the Hague summit. He threatened Russia with more sanctions (if, that is, Putin crosses the next red line). On Thursday, the UN General Assembly is expected to pass a non-binding resolution that declares the Russian annexation of Crimea null and void.

But mostly, Obama opines that Putin is yesterday’s man living in today’s world.

He’s absolutely right, incidentally: Heavily reliant on oil and gas exports, Russia’s economy risks collapse if energy prices dip. And US advances in shale technology promise abundant, cheap energy in the near future. So in theory Putin would do much better worrying about Russia’s economy than rebuilding a lost Soviet empire.

But Putin is who he is, and he’s playing his weak hand quite well, thank you very much. He just annexed Crimea without firing a shot, and he’s yet to feel any downside for it (other than not getting a tablet to play at The Hague, that is).

And while Putin maximizes Russia’s assets (or, rather, those of his oligarch cronies), our president models, simulates and theorizes.

As our economy recovers, albeit too slowly, Obama’s poll numbers are in the low 40s. As Russia’s economy sinks, Putin’s popularity soars at home — polls up to the 80s.

Maybe Putin’s 21st century model isn’t all that new — but since Obama, late to the game, has yet to respond adequately, Russia’s weak hand is beating America’s strong one.

Obama’s right on another front: He absolutely should worry about a bomb going off in this city.

But when he visits Riyadh on Friday, Obama is likely to have a tough time convincing his hosts that our diplomats will stop their enemy, Iran, from getting the Bomb. The Saudis warn that they will respond by acquiring their own nukes. Others in the region will follow.

And, simulation aside, that’s where terrorists would most likely get that Manhattan-bound nuke.

If loose nukes are the issue, Obama should concentrate his efforts on Teheran and its nuclear sites in Bushehr and Qum. And if maintaining the post-Cold War order is important, Obama must confront Russia in Ukraine.

Rather than confronting crises head-on, however, he talks and wags that finger.

In the 21st century, he apparently believes, simulation is the name of the game.